Efficient light coupling between an ultra-low loss lithium niobate waveguide and an adiabatically tapered single mode optical fiber

Abstract

A lithium niobate on insulator ridge waveguide allows constructing high-density photonic integrated circuits thanks to its small bending radius offered by the high index contrast. Meanwhile, the significant mode-field mismatch between an optical fiber and the single-mode lithium niobate waveguide leads to low coupling efficiencies. Here, we demonstrate, both numerically and experimentally, that the problem can be solved with a tapered single mode fiber of an optimized mode field profile. Numerical simulation shows that the minimum coupling losses for the TE and TM mode are 0.32 dB and 0.86 dB, respectively. Experimentally, though without anti-reflection coating, the measured coupling losses for TE and TM mode are 1.32 dB and 1.88 dB, respectively. Our technique paves a way for a broad range of on-chip lithium niobate applications.

8 pages, 5 figures

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Cited by in corpus (5)

• Integrated photonics on thin-film lithium niobate
• Intense optical parametric amplification in dispersion engineered nanophotonic lithium niobate waveguides
• Efficient self-imaging grating couplers on a Lithium-Niobate-On-Insulator platform at near-visible and telecom wavelengths
• High-index-contrast single-mode optical waveguides fabricated on lithium niobate by photolithography assisted chemo-mechanical etching (PLACE)
• High-efficient and polarization independent edge coupler for thin-film lithium niobite waveguide devices